1use crate::{
  2    element::{AnyElement, Element, IntoElement, Layout, ParentElement},
  3    interactive::{InteractionHandlers, Interactive},
  4    style::{Style, StyleHelpers, Styleable},
  5    ViewContext,
  6};
  7use anyhow::Result;
  8use gpui::{geometry::vector::Vector2F, platform::MouseMovedEvent, LayoutId};
  9use refineable::{CascadeSlot, Refineable, RefinementCascade};
 10use smallvec::SmallVec;
 11use std::{cell::Cell, rc::Rc};
 12
 13pub struct Hoverable<E: Styleable> {
 14    hovered: Rc<Cell<bool>>,
 15    cascade_slot: CascadeSlot,
 16    hovered_style: <E::Style as Refineable>::Refinement,
 17    child: E,
 18}
 19
 20pub fn hoverable<E: Styleable>(mut child: E) -> Hoverable<E> {
 21    Hoverable {
 22        hovered: Rc::new(Cell::new(false)),
 23        cascade_slot: child.style_cascade().reserve(),
 24        hovered_style: Default::default(),
 25        child,
 26    }
 27}
 28
 29impl<E: Styleable> Styleable for Hoverable<E> {
 30    type Style = E::Style;
 31
 32    fn style_cascade(&mut self) -> &mut RefinementCascade<Self::Style> {
 33        self.child.style_cascade()
 34    }
 35
 36    fn declared_style(&mut self) -> &mut <Self::Style as Refineable>::Refinement {
 37        &mut self.hovered_style
 38    }
 39}
 40
 41impl<V: 'static, E: Element<V> + Styleable> Element<V> for Hoverable<E> {
 42    type PaintState = E::PaintState;
 43
 44    fn layout(
 45        &mut self,
 46        view: &mut V,
 47        cx: &mut ViewContext<V>,
 48    ) -> Result<(LayoutId, Self::PaintState)>
 49    where
 50        Self: Sized,
 51    {
 52        Ok(self.child.layout(view, cx)?)
 53    }
 54
 55    fn paint(
 56        &mut self,
 57        view: &mut V,
 58        parent_origin: Vector2F,
 59        layout: &Layout,
 60        paint_state: &mut Self::PaintState,
 61        cx: &mut ViewContext<V>,
 62    ) where
 63        Self: Sized,
 64    {
 65        let bounds = layout.bounds + parent_origin;
 66        self.hovered.set(bounds.contains_point(cx.mouse_position()));
 67
 68        let slot = self.cascade_slot;
 69        let style = self.hovered.get().then_some(self.hovered_style.clone());
 70        self.style_cascade().set(slot, style);
 71
 72        let hovered = self.hovered.clone();
 73        cx.on_event(layout.order, move |_view, _: &MouseMovedEvent, cx| {
 74            cx.bubble_event();
 75            if bounds.contains_point(cx.mouse_position()) != hovered.get() {
 76                cx.repaint();
 77            }
 78        });
 79
 80        self.child
 81            .paint(view, parent_origin, layout, paint_state, cx);
 82    }
 83}
 84
 85impl<E: Styleable<Style = Style>> StyleHelpers for Hoverable<E> {}
 86
 87impl<V: 'static, E: Interactive<V> + Styleable> Interactive<V> for Hoverable<E> {
 88    fn interaction_handlers(&mut self) -> &mut InteractionHandlers<V> {
 89        self.child.interaction_handlers()
 90    }
 91}
 92
 93impl<V: 'static, E: ParentElement<V> + Styleable> ParentElement<V> for Hoverable<E> {
 94    fn children_mut(&mut self) -> &mut SmallVec<[AnyElement<V>; 2]> {
 95        self.child.children_mut()
 96    }
 97}
 98
 99impl<V: 'static, E: Element<V> + Styleable> IntoElement<V> for Hoverable<E> {
100    type Element = Self;
101
102    fn into_element(self) -> Self::Element {
103        self
104    }
105}